In the United Kingdom, “practice” is the noun, “practise” the verb; but in the U.S. the spelling “practice” is commonly used for both, though the distinction is sometimes observed. “Practise” as a noun is, however, always wrong in both places: a doctor always has a “practice,” never a “practise.”
Source : http://www.wsu.edu
We may compare with the following explanation :
Practice is a noun
For example: We need to put these ideas into practice.
Practise is a verb
For example: To learn English well you have to practise.
Both of them is correct. We have to know when we use practice and practise
Source : http://www.learnenglish.de